Today I tried to remove a user from SQL server database and encountered this error:

The database principal owns a schema in the database, and cannot be dropped (Microsoft SQL Server, Error: 15138)

Followed this link from TechNet at http://blogs.technet.com/b/mdegre/archive/2010/12/19/the-database-principal-owns-a-schema-in-the-database-and-cannot-be-dropped.aspx

Here were the steps I took to drop the user “syang”:

1. Find the schema name by running this query:

   select * from sys.schemas where principal_id=USER_ID('syang')

   which returned:

    db_owner 16384 6 (name, schema_id, and principal_id)

2. Run this query to alter the schema name:

   alter authorization on schema::db_owner to dbo
   go

3. Now, I was able to drop the user syang successfully by running this query:

   drop user syang

4. To remove user login syang completely from the SQL server, run this:

   IF  EXISTS (SELECT * FROM sys.server_principals WHERE name ='syang')
   DROP LOGIN syang 
   GO